US20180213489A1 - User device, base station, communication method, and instruction method - Google Patents
User device, base station, communication method, and instruction method Download PDFInfo
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- US20180213489A1 US20180213489A1 US15/578,398 US201615578398A US2018213489A1 US 20180213489 A1 US20180213489 A1 US 20180213489A1 US 201615578398 A US201615578398 A US 201615578398A US 2018213489 A1 US2018213489 A1 US 2018213489A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/30—TPC using constraints in the total amount of available transmission power
- H04W52/36—TPC using constraints in the total amount of available transmission power with a discrete range or set of values, e.g. step size, ramping or offsets
- H04W52/367—Power values between minimum and maximum limits, e.g. dynamic range
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
- H04W16/24—Cell structures
- H04W16/32—Hierarchical cell structures
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/06—TPC algorithms
- H04W52/14—Separate analysis of uplink or downlink
- H04W52/146—Uplink power control
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/38—TPC being performed in particular situations
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W72/00—Local resource management
- H04W72/04—Wireless resource allocation
- H04W72/044—Wireless resource allocation based on the type of the allocated resource
- H04W72/0446—Resources in time domain, e.g. slots or frames
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
- H04W52/04—TPC
- H04W52/30—TPC using constraints in the total amount of available transmission power
- H04W52/34—TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
- H04W52/346—TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading distributing total power among users or channels
Definitions
- the present invention relates to a user device, a base station, a communication method, and an instruction method.
- a Long Term Evolution (LTE) system employs carrier aggregation (CA) where communications are performed using multiple carriers at the same time and using a predetermined bandwidth (maximum of 20 MHz) as a base unit.
- CA carrier aggregation
- a carrier used as a base unit in the carrier aggregation is referred to as a component carrier (CC).
- a primary cell (PCell) and a secondary cell (SCell) are set for a user device.
- the PCell is a highly-reliable cell and secures connectivity
- the SCell is a subsidiary cell.
- the user device primarily connects to the PCell and can add the SCell as necessary.
- the PCell is substantially the same as an independent cell that supports radio link monitoring (RLM) and semi-persistent scheduling (SPS).
- RLM radio link monitoring
- SPS semi-persistent scheduling
- the SCell is a cell that is set for the user device in addition to the PCell. Addition and removal of the SCell is performed by radio resource control (RRC) signaling. Immediately after the SCell is set for the user device, the SCell is in a deactivated state and becomes able to perform communications (able to perform scheduling) only after being activated. In CA of LTE Rel-10, multiple CCs under the same base station are used.
- RRC radio resource control
- Rel-12 defines “dual connectivity” (DC) that performs simultaneous communication using CCs under different base stations to achieve high throughput. That is, in the dual connectivity, the user device performs communications using radio resources of two physically-separate base stations at the same time.
- DC dual connectivity
- the dual connectivity is a type of CA, which may also be referred to as “inter-eNB CA”, and uses a master eNB (MeNB) and a secondary eNB (SeNB).
- MeNB master eNB
- SeNB secondary eNB
- CA performed using the same base station is referred to as “intra-eNB CA” to distinguish it from “inter-eNB CA”.
- a cell group composed of one or more cells under the MeNB is referred to as a master cell group (MCG), and a cell group composed of one or more cells under the SeNB is referred to as a secondary cell group (SCG).
- MCG master cell group
- SCG secondary cell group
- Uplink CCs are set in at least one SCell in the SCG
- PUCCH is set in one of the uplink CCs.
- This SCell is referred to as a primary SCell (PSCell).
- the base station controls the transmission power of the user device (transmission power control (TPC)). More specifically, the user device determines the transmission power based on, for example, maximum transmission power (PcmA) with which the user device can transmit an uplink signal, an estimated value of path loss (PL) of a downlink signal, a signal transmission bandwidth, and a power control command (TPC command) from the base station (Non-Patent Document 1).
- PcmA maximum transmission power
- PL path loss
- TPC command power control command
- an upper limit is set for the maximum transmission power (P CMAX ) of each user device to reduce interference.
- the upper limit of the maximum transmission power is referred to as “P CMAX _ H ”.
- MPR maximum power reduction
- A-MPR additional maximum power reduction
- the fifth-generation (5G) radio communication technologies are being considered.
- 5G to achieve a low delay, it is being considered to make the TTI length, which is a minimum unit of scheduling, shorter than the TTI length (1 ms) in LTE. Accordingly, there is a possibility that CA is performed using a combination of cells (CCs) with different TTI lengths.
- One object of this disclosure is to solve or reduce the above-described problems, and to provide a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- An aspect of this disclosure provides a user device for a radio communication system that supports uplink carrier aggregation.
- the user device includes a transmitter that transmits an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and a calculator that calculates a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe.
- the base station includes a receiver that receives an uplink signal from a user device, and an instructor that instructs the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier.
- An aspect of this disclosure provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- FIG. 1 is a drawing used to describe calculation methods of P CMAX _ L in UL CA and sync DC;
- FIG. 2 is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in async DC;
- FIG. 3 is a drawing illustrating an example of a configuration of a radio communication system according to an embodiment
- FIG. 4A is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated;
- FIG. 4B is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated;
- FIG. 5A is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different and variable TTI lengths are aggregated;
- FIG. 5B is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different and variable TTI lengths are aggregated;
- FIG. 6 is a sequence chart illustrating a process performed by a radio communication system according to an embodiment
- FIG. 7 is a drawing illustrating a process of switching calculation methods
- FIG. 8 is a drawing used to describe calculation methods (variation 1) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated;
- FIG. 9 is a drawing used to describe calculation methods (variation 2) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated;
- FIG. 10 is a drawing used to describe calculation methods (variation 3) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated;
- FIG. 11 is a drawing illustrating an example of a functional configuration of a user device according to an embodiment
- FIG. 12 is a drawing illustrating an example of a functional configuration of a base station according to an embodiment
- FIG. 13 is a drawing illustrating an example of a hardware configuration of a user device according to an embodiment.
- FIG. 14 is a drawing illustrating an example of a hardware configuration of a base station according to an embodiment.
- LTE Long Term Evolution
- the embodiments of the present invention may also be applied to a radio communication system where the TTI length is different from the subframe length.
- the embodiments of the present invention may be applied to a radio communication system where the TTI length is different from the subframe length by replacing “TTI length” in the descriptions below with “subframe length”.
- Non-Patent Document 2 specifies that the maximum transmission power (P CMAX ) of each user device is a value that falls within a range between P CMAX _ L and P CMAX _ H .
- Non-Patent Document 2 also specifies that P CMAX _ L and P CMAX _ H of a user device are calculated, respectively, by formula (2) and formula (3) below.
- a serving cell in formula (2) and formula (3) indicates an uplink CC used for communication.
- P CMAX _ L is obtained by calculating power levels for respective CCs (by using a formula corresponding to “calculated for each serving cell (c)” in formula (2)), and selecting a smaller one of a sum (E) of the calculated power levels of CCs and P powerclass .
- the upper limit of “P CMAX _ L ” is P powerclass .
- P CMAX _ H is obtained by selecting a smaller one of a sum of the values of P-Max specified by the network for respective CCs and P powerclass .
- the upper limit of “P CMAX _ H ” is P powerclass .
- P CMAX _ L (x,y) indicates P CMAX _ L that is calculated by pairing a subframe x of a specific CC and a subframe y of another CC different from the specific CC.
- P CMAX _ L (x,y) indicates a smaller one of a sum of a power level calculated from various parameters of the subframe x (e.g., P EMAX,c , mpr c ) and a power level calculated from various parameters of the subframe y (e.g., P EMAX,c , mpr c ) and P powerclass .
- P CMAX _ H (x,y) indicates P CMAX _ H that is calculated by pairing a subframe x of a specific CC and a subframe y of another CC different from the specific CC.
- P CMAX _ H (x,y) indicates a smaller one of a sum of P EMAX in the subframe x and P EMAX in the subframe y and P powerclass .
- FIG. 1 is a drawing used to describe calculation methods of P CMAX _ L in UL CA and sync DC.
- FIG. 1 ( a 1 ) illustrates a state where subframes are synchronized in uplink CA using CC#1 and CC#2.
- P CMAX _ L in respective subframes can be expressed as P CMAX _ L (i,i) and P CMAX _ L (i+1,i+1).
- Non-Patent Document 2 specifies that in a portion where a subframe i and a subframe i+1 overlap each other, a smaller one of P CMAX _ L (i,i) in the subframe i and P CMAX _ L (i+1,i+1) in the subframe i+i is selected as P CMAX _ L .
- FIG. 1 ( b 1 ) and FIG. 1 ( b 2 ) illustrates a calculation method of “P CMAX _ L ” in sync DC.
- the sync DC is a type of DC that is operated such that the boundaries of subframes of CCs constituting MCG and SCG are almost aligned with each other.
- FIG. 1 ( b 1 ) illustrates a state where the subframes of CC#1 and CC#2 are synchronized with each other.
- “P CMAX _ L ” in respective subframes can be expressed as P CMAX _ L (p,q) and P CMAX _ L (p+1,q+1) Also in the sync DC, as illustrated by FIG.
- Non-Patent Document 2 specifies that in a portion where the subframes overlap each other, a smaller one of P CMAX _ L (p,q) and P CMAX _ L (p+1, q+1) is selected as P CMAX _ L .
- FIG. 2 is a drawing used to describe calculation methods of P CMAX _ L and P CMAX _ H in async DC.
- the async DC is a type of DC that is operated such that the boundaries of subframes of CCs constituting MCG and SCG are greatly misaligned with each other.
- Non-Patent Document 2 specifies different calculation methods of “P CMAX _ L ” and “P CMAX _ H ” for a case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG and a case where the subframe of the CC in SCG is ahead of the subframe of the CC in MCG.
- the case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG indicates that the difference between the start point of the subframe of the CC in MCG and the start point of the subframe of the CC in SCG (the SCG subframe that is behind the MCG subframe) is less than or equal to 0.5 ms.
- FIG. 2 ( a ) illustrates calculation methods for the case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG.
- Non-Patent Document 2 specifies that when the subframe of the CC in MCG is ahead of the subframe of the CC in SCG, an MCG subframe is set as a reference subframe, and a smaller one of two values of “P CMAX _ L ” obtained by pairing the reference subframe with each of two SCG subframes overlapping the reference subframe is selected as “P CMAX _ L ”.
- Non-Patent Document 2 specifies that a larger one of two values of “P CMAX _ H ” obtained by pairing the reference subframe with each of two SCG subframes overlapping the reference subframe is selected as “P CMAX _ H ”. Specifically, as illustrated in FIG. 2 ( a ) , a smaller one of P CMAX _ L (p,q) and P CMAX _ L (p,q ⁇ 1) is selected as “P CMAX _ L ” for the period of the subframe p, and a larger one of P CMAX _ H (p,q) and P CMAX _ H (p,q ⁇ 1) is selected as “P CMAX _ H ” for the period of the subframe p. Also for other subframes ( . . . , p ⁇ 1, p+1, P+2, . . . ), “P CMAX _ L ” and “P CMAX _ H ” are calculated according to the same methods.
- FIG. 2 ( b ) illustrates calculation methods for the case where the subframe of the CC in SCG is ahead of the subframe of the CC in MCG.
- an SCG subframe is set as a reference subframe, and “P CMAX _ L ” and “P CMAX _ H ” are calculated according to methods similar to those of FIG. 2 ( a ) .
- FIG. 3 is a drawing illustrating an example of a configuration of a radio communication system according to an embodiment.
- the radio communication system of the present embodiment includes a user device UE, a base station eNBa forming a cell “a”, and a base station eNBb forming a cell “b”.
- the base station eNBa and the base station eNBb may be collectively referred to as a “base station eNB” when distinction is not necessary.
- FIG. 3 includes only one user device UE, the radio communication system may include multiple user devices UE. Also, although FIG. 3 includes the base station eNBa and the base station eNBb, the radio communication system may include one base station eNB or three or more base stations eNB. Also in FIG. 3 , although the base station eNBa forms the cell “a” and the base station eNBb forms the cell “b”, each of the base station eNBa and the base station eNBb may form multiple cells. Also, the base station eNBa and the base station eNBb may be an MeNB and an SeNB or an SeNB and an MeNB, respectively.
- CA in the present embodiment may be intra-eNB CA, inter-eNB CA, or a combination of intra-eNB CA and inter-eNB CA.
- each of the cell “a” and the cell “b” includes a downlink CC and an uplink CC.
- each of the cell “a” and the cell “b” may include only an uplink CC.
- the TTI length of the uplink CC of the cell “a” is different from the TTI length of the uplink CC of the cell “b”.
- both of the cell “a” and the cell “b” may be 5G cells.
- the user device UE performs uplink CA between a CC of the cell “a” and a CC of the cell “b”.
- the user device UE may also be configured to perform uplink CA by aggregating three or more CCs.
- the communication scheme for the uplink CC may be Single-Carrier Frequency-Division Multiple Access (SC-FDMA) as in LTE, orthogonal frequency-division multiplexing (OFDM), or any other communication scheme.
- SC-FDMA Single-Carrier Frequency-Division Multiple Access
- OFDM orthogonal frequency-division multiplexing
- the user device UE of the present embodiment may be configured to define each subframe of a CC with a long TTI length as a reference subframe, and to calculate “P CMAX _ L ” and “P CMAX _ H ” using formulas (2) and (3) described above.
- a method where each subframe of a CC with a long TTI length is defined as a reference subframe and “P CMAX _ L ” and “P CMAX _ H ” are calculated using formulas (2) and (3) described above is referred to as a “calculation method 1”.
- the user device UE combines the reference subframe of the CC having the long TTI length with respective subframes of a CC having a short TTI length that are included between the start point and the end point of the reference subframe and with respective subframes of the CC having the short TTI length that cross one of the start point and the end point of the reference subframe, and calculates “P CMAX _ L ” for the period of the reference subframe by selecting the smallest “P CMAX _ L ” from “P CMAX _ L ” values calculated for the respective combinations.
- the user device UE calculates “P CMAX _ H ” for the period of the reference subframe by selecting the largest “P CMAX _ H ” from “P CMAX _ H ” values calculated for the respective combinations.
- FIGS. 4A and 4B are drawings used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated. An example is described with reference to FIG. 4A .
- the user device UE selects the smallest one of P CMAX _ L (p,q ⁇ 1), P CMAX _ L (p,q), P CMAX _ L (p,q+1), and P CMAX _ L (p,q+n) as “P CMAX _ L ” for the period of the subframe p (reference subframe).
- the user device UE selects the largest one of P CMAX _ H (p,q ⁇ 1), P CMAX _ H (p,q) P CMAX _ H (p,q+1), and P CMAX _ H (p,q+n) as “P CMAX _ H ” for the period of the subframe p.
- the user device UE can continuously calculate “P CMAX _ L ” and “P CMAX _ H ” while performing uplink communications by performing this process for each subframe of CC#1.
- Calculating “P CMAX _ L ” and “P CMAX _ H ” with the calculation method 1 makes the maximum transmission power (P CMAX ) constant in each subframe of the CC with the long TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB providing the CC with the long TTI length due to power drop in the same subframe. That is, using the calculation method 1 makes it possible to prevent degradation in the communication quality of the CC with the long TTI length.
- the user device UE of the present embodiment may also be configured to define each subframe of the CC with the short TTI length as a reference subframe, and to calculate “P CMAX _ L ” and “P CMAX _ H ” using formulas (2) and (3) described above.
- a method where each subframe of the CC with the short TTI length is defined as a reference subframe and “P CMAX _ L ” and “P CMAX _ H ” are calculated using formulas (2) and (3) described above is referred to as a “calculation method 2”.
- the user device UE calculates “P CMAX _ L ” for the period of the reference subframe by selecting the smaller “P CMAX _ L ” from “P CMAX _ L ” values calculated for the combinations of the reference subframe and respective two subframes of the CC with the long TTI length that are located before and after the subframe boundary.
- the user device UE calculates “P CMAX _ H ” for the period of the reference subframe by selecting the larger “P CMAX _ H ” from “P CMAX _ H ” values calculated for the respective combinations.
- the user device UE calculates “P CMAX _ L ” and “P CMAX _ H ” by using the combination of the reference subframe and a subframe of the CC with the long TTI length that includes the start point and the end point of the reference subframe.
- a subframe q ⁇ 1 crosses the boundary between a subframe p ⁇ 1 and a subframe p.
- the user device UE selects the smaller one of P CMAX _ L (p ⁇ 1,q ⁇ 1) and P CMAX _ L (p,q ⁇ 1) as “P CMAX _ L ” for the period of the subframe q ⁇ 1 (reference subframe).
- the user device UE selects the larger one of P CMAX _ H (p ⁇ 1,q ⁇ 1) and P CMAX _ H (p,q ⁇ 1) as “P CMAX _ H ” for the period of the subframe q ⁇ 1.
- the user device UE also calculates “P CMAX _ L ” and “P CMAX _ H ” for a subframe q+n (reference subframe) crossing the boundary between the subframe p and a subframe p+1 in a similar manner.
- a subframe q does not cross any subframe boundary of CC#1 (i.e., the subframe q is included in the period of the subframe p).
- the user device UE uses P CMAX _ L (p,q) and P CMAX _ H (p,q) as “P CMAX _ L ” and “P CMAX _ H ” for the period of the subframe q (reference subframe).
- the user device UE also calculates “P CMAX _ L ” and “P CMAX _ H ” for a subframe q+1 that does not cross any subframe boundary of CC#1 in a similar manner.
- the user device UE can continuously calculate “P CMAX _ L ” and “P CMAX _ H ” while performing uplink communications by performing this process for each subframe of CC#2.
- Calculating “P CMAX _ L ” and “P CMAX _ H ” with the calculation method 2 makes the maximum transmission power (P CMAX ) constant in each subframe of the CC with the short TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB providing the CC with the short TTI length due to power drop in the same subframe.
- using the calculation method 1 has an advantage of making “P CMAX _ L ” constant in each subframe of the CC with the long TTI length.
- the calculation method 1 there is a risk, for example, that the maximum transmission power is set at an unnecessarily low value for some of subframes of the CC with the short TTI length that overlap the subframe of the CC with the long TTI length, and the coverage of an area corresponding to the CC with the short TTI length is reduced.
- Using the calculation method 2 does not cause such a problem and makes it possible to prevent the reduction in area coverage. That is, using the calculation method 2 makes it possible to prevent degradation in the communication quality of the CC with the short TTI length.
- the maximum transmission power (P CMAX ) of each user device is set at a value within a range between P CMAX _ L and P CMAX _ H .
- FIGS. 5A and 5B are drawings used to describe calculation methods of P CMAX _ L and P CMAX _ H in a case where CCs with different and variable TTI lengths are aggregated.
- FIGS. 5A and 5B illustrate a case where the TTI length (subframe length) of CC#2 is variable and the TTI length of the subframe q is different from that in FIGS. 4A and 4B .
- the user device UE may calculate “P CMAX _ L ” and “P CMAX _ H ” using one of the calculation method 1 and the calculation method 2.
- Calculation methods of “P CMAX _ L ” and “P CMAX _ H ” for each subframe in FIGS. 5A and 5B are substantially the same as those described with reference to FIGS. 4A and 4B , and therefore their descriptions are omitted here.
- the user device UE may be configured to always use the calculation method 1 (i.e., to set a subframe of the CC with the long TTI length as a reference frame) to calculate “P CMAX _ L ” and “P CMAX _ H ”, or to always use the calculation method 2 (i.e., to set a subframe of the CC with the short TTI length as a reference frame) to calculate “P CMAX _ L ” and “P CMAX _ H ”
- the user device UE may be configured to select whether to use the calculation method 1 or the calculation method 2 to calculate “P CMAX _ L ” and “P CMAX _ H ” according to an instruction from the base station eNB.
- the user device UE may be configured to calculate “P CMAX _ L ” and “P CMAX _ H ” using the calculation method 1 when an instruction signal (S 11 ) from the base station eNB includes information indicating the calculation method 1, and to calculate “P CMAX _ L ” and “P CMAX _ H ” using the calculation method 2 when the instruction signal includes information indicating the calculation method 2.
- the instruction signal may be a physical layer (PHY) signal, a MAC layer signal, or an RRC signal.
- the instruction signal may be transmitted from either one of the LTE (4G) base station eNB and the 5G base station eNB.
- the user device UE may be configured to give priority to the instruction signal from the LTE (4G) base station eNB (i.e., follow the instruction signal from the LTE (4G) base station eNB), or to give priority to the instruction signal from the 5G base station eNB (i.e., follow the instruction signal from the 5G base station eNB).
- the base station eNB may be configured to instruct the user device UE whether to use the calculation method 1 or the calculation method 2 based on the communication quality (e.g., reference signal received quality (RSRQ), reference signal received power (RSRP), or channel quality indicator (CQI)) of each CC (the downlink CC of each cell constituting CA) reported from the user device UE.
- the communication quality e.g., reference signal received quality (RSRQ), reference signal received power (RSRP), or channel quality indicator (CQI)
- RSRQ reference signal received quality
- RSRP reference signal received power
- CQI channel quality indicator
- the user device UE may be configured to select by itself whether to use the calculation method 1 or the calculation method 2 to calculate “P CMAX _ L ” and “P CMAX _ H ”.
- the user device UE may be configured to measure and compare the communication quality levels (e.g., RSRQ, RSRP, or CQI) of downlink CCs of cells (downlink CCs of the same cells as those providing uplink CCs to be aggregated) to select whether to use the first calculation method 1 or the second calculation method 2.
- the communication quality levels e.g., RSRQ, RSRP, or CQI
- the user device UE may be configured to report to the base station eNB whether the calculation method 1 or the calculation method 2 has been used. For example, as illustrated by FIG. 6 ( b ) , the user device UE may be configured to transmit, to the base station eNB, a report signal (S 21 ) including information indicating whether the calculation method 1 or the calculation method 2 has been used.
- the report signal may be a physical layer (PHY) signal, a MAC layer signal, or an RRC signal.
- the user device UE may be configured to switch between the calculation method 1 and the calculation method 2 to calculate “P CMAX _ L ” and “P CMAX _ H ” at a predetermined timing.
- FIG. 7 is a drawing illustrating a process of switching calculation methods. In the example of FIG. 7 , the calculation methods are switched at the timing of each of step S 51 and step S 52 .
- the user device UE may be configured to switch the calculation methods according to an instruction from the base station eNB or based on its own decision.
- the base station eNB may transmit an instruction signal (S 11 in FIG. 6 ( a )) to the user device UE, and the user device UE may switch the calculation methods at a timing when the instruction signal is received.
- the timing when the user device UE switches the calculation methods may be at a subframe boundary of the CC with the short (or long) TTI length, or may be after a predetermined period of time from the timing when the user device UE decides to switch the calculation methods (or the timing when an instruction to switch the calculation methods is received from the base station eNB).
- the calculation methods may be switched at any other appropriate timing.
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) the calculation methods depending on whether priority is given to the communication quality of the CC with the long TTI length or the communication quality of the CC with the short TTI length.
- the user device UE or the base station eNB may be configured to compare the amounts of data to be transmitted using respective uplink CCs and to switch (or instruct to switch) the calculation methods such that priority is given to the communication quality of one of the CCs with which a larger amount of data is to be transmitted.
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) the calculation methods such that priority is given to the communication quality of a CC for which a high-priority bearer (e.g., a bearer with a small QoS class identifier (QCI)) is set.
- a high-priority bearer e.g., a bearer with a small QoS class identifier (QCI)
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) to the calculation method 1 at a timing when the communication quality of the CC with the long TTI length becomes good and to switch (or instruct to switch) to the calculation method 2 at a timing when the communication quality of the CC with the short TTI length becomes good, based on the communication quality levels (e.g., RSRQ, RSRP, or CQI) of the CCs.
- the communication quality levels e.g., RSRQ, RSRP, or CQI
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) to the calculation method 2 at a timing when the communication quality of the CC with the long TTI length becomes good and to switch (or instruct to switch) to the calculation method 1 at a timing when the communication quality of the CC with the short TTI length becomes good.
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) to the calculation method 1 at a timing when the CC with the long TTI length is attached to MCG and to switch (or instruct to switch) to the calculation method 2 at a timing when the CC with the short TTI length is attached to MCG.
- the user device UE or the base station eNB may be configured to switch (or instruct to switch) to the calculation method 2 at a timing when the CC with the long TTI length is attached to MCG and to switch (or instruct to switch) to the calculation method 1 at a timing when the CC with the short TTI length is attached to MCG.
- one of two cell groups (CGs) including a PCell is MCG and another one of the CGs including no PCell is SCG.
- MCG one of two cell groups (CGs) including a PCell
- SCG another one of the CGs including no PCell
- the CC with the long (or short) TTI length is attached to MCG indicates a case where a CG including the PCell changes to another CG due to, for example, handover.
- the user device UE or the base station eNB may be configured to switch (or to instruct to switch) between the calculation method 1 and the calculation method 2 based on operational states of CCs.
- the user device UE or the base station eNB may be configured to switch (or to instruct to switch) to the calculation method 2 when the CC with the long TTI length is deactivated, the TA timer of the CC is stopped, uplink transmission (e.g., SRS, PUCCH, or PUSCH) with the CC is not being performed, the CC transitions to a DRX state, or the CC transitions to a measurement gap state.
- uplink transmission e.g., SRS, PUCCH, or PUSCH
- the user device UE or the base station eNB may be configured to switch (or to instruct to switch) to the calculation method 1 when the CC with the short TTI length is deactivated, the TA timer of the CC is stopped, uplink transmission (e.g., SRS, PUCCH, or PUSCH) with the CC is not being performed, the CC transitions to a DRX state, or the CC transitions to a measurement gap state.
- uplink transmission e.g., SRS, PUCCH, or PUSCH
- the user device UE may be configured to calculate “P CMAX _ L ” and “P CMAX _ H ” using a combination of the calculation method 1, the calculation method 2, and the related-art calculation method. Variations of calculation methods are described below.
- FIG. 8 is a drawing used to describe a calculation method (variation 1) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated.
- uplink CA is performed using CC#1 and CC#2 belonging to MCG and CC#3 and CC#4 belonging to SCG.
- the subframe intervals of CC#1 and CC#2 are the same, and the subframes of CC#1 and CC#2 are synchronized with each other. Also, the subframe intervals of CC#3 and CC#4 are the same, and the subframes of CC#3 and CC#4 are synchronized with each other. On the other hand, the subframe interval (TTI length) of CC#1 and CC#2 is different from the subframe interval (TTI length) of CC#3 and CC#4.
- P CMAX _ L and P CMAX _ H are first calculated for the combinations of subframes of CC#1 and CC#2 using the related-art calculation method (the calculation method of FIG. 1 ( a 1 ) or FIG. 1 ( b 1 )), and the calculated P CMAX _ L and P CMAX _ H are set as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- P CMAX _ L and P CMAX _ H are calculated for the combinations of subframes of CC#3 and CC#4 using the related-art calculation method (the calculation method of FIG. 1 ( a 1 ) or FIG. 1 ( b 1 )), and the calculated P CMAX _ L and P CMAX _ H are set as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#3.
- P CMAX _ L and P CMAX _ H are calculated for the combinations of subframes of CC#2 and CC#3 according to the calculation method 1 or the calculation method 2.
- P CMAX _ L is obtained for a combination of tentative “P CMAX _ L ” of a subframe x of CC#2 and tentative “P CMAX _ L ” of a subframe y of CC#3.
- the tentative “P CMAX _ L ” of a subframe x of CC#2 and the tentative “P CMAX _ L ” of a subframe y of CC#3 are summed. This calculation corresponds to summing ( ⁇ ) values “calculated for each serving cell (c)” in formula (2).
- P CMAX _ H is obtained for a combination of tentative “P CMAX _ H ” of the subframe x of CC#2 and the tentative “P CMAX _ H ” of the subframe y of CC#3.
- the tentative “P CMAX _ H ” of a subframe x of CC#2 and the tentative “P CMAX _ H ” of the subframe y of CC#3 are summed. This calculation corresponds to “calculated for each serving cell (c), and calculated values are totaled” in formula (3).
- the above described calculation method of P CMAX _ L is equivalent to a process of calculating P CMAX _ L values of subframes of respective CCs using the part “calculated for each serving cell (c)” of formula (2), summing the calculated P CMAX _ L values of the CCs, using the sum as P CMAX _ L when the sum is less than P powerclass , and using P powerclass as P CMAX _ L when the sum is greater than or equal to P powerclass .
- the above described calculation method of P CMAX _ H is equivalent to a process of summing P EMAX values of subframes of respective CCs, using the sum as P CMAX _ H when the sum is less than P powerclass , and using P powerclass as P CMAX _ H when the sum is greater than or equal to P powerclass .
- FIG. 8 ( a ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 1
- FIG. 8 ( b ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 2.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#1 and CC#2 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE also calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#3 and CC#4 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#3.
- the user device UE sets each subframe of CC#2 as a reference subframe, and calculates “P CMAX _ L ” and “P CMAX _ H ” for the combinations of subframes of CC#2 and CC#3 by using the calculation method 1.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#1 and CC#2 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE also calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#3 and CC#4 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#3.
- the user device UE sets each subframe of CC#3 as a reference subframe, and calculates “P CMAX _ L ” and “P CMAX _ H ” for the combinations of subframes of CC#2 and CC#3 by using the calculation method 2.
- FIG. 9 is a drawing used to describe a calculation method (variation 2) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated.
- uplink CA is performed using CC#1 belonging to MCG and CC#2 and CC#3 belonging to SCG.
- the subframe intervals of CC#1 and CC#2 are different from each other, and the subframe intervals of CC#2 and CC#3 are also different from each other.
- P CMAX _ L and P CMAX _ H are first calculated for the combinations of subframes of CC#2 and CC#3 using the calculation method 1 (using each subframe of CC#2 as a reference subframe), and the calculated P CMAX _ L and P CMAX _ H are set as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- P CMAX _ L and P CMAX _ H are calculated for the combinations of subframes of CC#1 and CC#2 according to the calculation method 1 or the calculation method 2.
- FIG. 9 ( a ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 1
- FIG. 9 ( b ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 2.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#2 and CC#3 using the calculation method 1, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE sets each subframe of CC#1 as a reference subframe, and calculates “P CMAX _ L ” and “P CMAX _ H ” for the combinations of subframes of CC#1 and CC#2 by using the calculation method 1.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#2 and CC#3 using the calculation method 1, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE sets each subframe of CC#2 as a reference subframe, and calculates “P CMAX _ L ” and “P CMAX _ H ” for the combinations of subframes of CC#1 and CC#2 by using the calculation method 2.
- FIG. 10 is a drawing used to describe a calculation method (variation 3) of P CMAX _ L and P CMAX _ H in a case where CCs with different TTI lengths are aggregated.
- uplink CA is performed using CC#1 belonging to MCG and CC#2 and CC#3 belonging to SCG.
- the subframe intervals of CC#2 and CC#3 are the same, but the subframes of CC#2 and CC#3 are not synchronized with each other. Also, the subframe intervals of CC#1 and CC#2 are different from each other.
- P CMAX _ L and P CMAX _ H are first calculated for the combinations of subframes of CC#2 and CC#3 using the related-art calculation method (the calculation method of FIG. 2 ( a ) ), and the calculated P CMAX _ L and P CMAX _ H are set as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- P CMAX _ L and P CMAX _ H are calculated for the combinations of subframes of CC#1 and CC#2 according to the calculation method 1 or the calculation method 2.
- FIG. 10 ( a ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 1
- FIG. 10 ( b ) illustrates a case where P CMAX _ L and P CMAX _ H are calculated using the calculation method 2.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#2 and CC#3 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE sets each subframe of CC#1 as a reference subframe, and calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#1 and CC#2 by using the calculation method 1.
- the user device UE calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#2 and CC#3 using the related-art calculation method, and sets the calculated P CMAX _ L and P CMAX _ H as tentative P CMAX _ L and P CMAX _ H for the subframes of CC#2.
- the user device UE sets each subframe of CC#2 as a reference subframe, and calculates P CMAX _ L and P CMAX _ H for the combinations of subframes of CC#1 and CC#2 by using the calculation method 2.
- the user device UE may be configured to handle multiple consecutive subframes as one reference subframe in the calculation method 2. For example, in the example of FIG. 4B , the user device UE may handle two consecutive subframes (p and p+1) as one reference subframe. Because there may be cases where the values of P CMAX _ L and P CMAX _ H do not frequently change, this method makes it possible to reduce the processing load of the user device UE.
- FIG. 11 is a drawing illustrating an example of a functional configuration of a user device according to an embodiment.
- the user device UE includes a signal transmitter 101 , a signal receiver 102 , and a calculator 103 .
- FIG. 11 illustrates only functional components of the user device UE that are particularly relevant to the present embodiment, and the user device UE may also at least include unshown functional components that are necessary for operations conforming to LTE.
- the functional configuration of FIG. 11 is just an example. As long as operations related to the present embodiment can be performed, the categorization and the names of the functional components may be freely changed.
- the signal transmitter 101 includes a function to wirelessly transmit various physical layer signals.
- the signal receiver 102 includes a function to wirelessly receive various signals from the base station eNB, and obtain upper layer signals from the received physical layer signals.
- Each of the signal transmitter 101 and the signal receiver 102 includes a function to perform CA communications by aggregating multiple CCs. Also, each of the signal transmitter 101 and the signal receiver 102 includes a function to perform CA communications according to DC between MeNB and SeNB.
- the calculator 103 includes a function to calculate P CMAX _ L and P CMAX _ H for an uplink signal according to predetermined formulas using one of a subframe of a CC with a long TTI length and a subframe of a CC with a short TTI length as a reference subframe.
- the calculator 103 may be configured to select, based on an instruction from the base station eNB or downlink communication quality, whether to calculate P CMAX _ L and P CMAX _ H according to the predetermined formulas using the subframe of the CC with the long TTI length as the reference subframe or to calculate P CMAX _ L and P CMAX _ H according to the predetermined formulas using the subframe of the CC with the short TTI length as the reference subframe.
- the calculator 103 may be configured to switch, at a predetermined timing, between a method of calculating P CMAX _ L and P CMAX _ H according to the predetermined formulas using the subframe of the CC with the long TTI length as the reference subframe and a method of calculating P CMAX _ L and P CMAX _ H according to the predetermined formulas using the subframe of the CC with the short TTI length as the reference subframe.
- the predetermined timing may be determined according to the criteria described in “SWITCHING BETWEEN CALCULATION METHOD 1 AND CALCULATION METHOD 2”.
- FIG. 12 is a drawing illustrating an example of a functional configuration of a base station according to an embodiment.
- the base station eNB includes a signal transmitter 201 , a signal receiver 202 , and an instructor 203 .
- FIG. 12 illustrates only functional components of the base station eNB that are particularly relevant to the present embodiment, and the base station eNB may also at least include unshown functional components that are necessary for operations conforming to LTE.
- the functional configuration of FIG. 12 is just an example. As long as operations related to the present embodiment can be performed, the categorization and the names of the functional components may be freely changed.
- the signal transmitter 201 includes a function to wirelessly transmit various physical layer signals.
- the signal receiver 202 includes a function to wirelessly receive various signals from the user devices UE, and obtain upper layer signals from the received physical layer signals.
- Each of the signal transmitter 201 and the signal receiver 202 includes a function to perform CA communications by aggregating multiple CCs.
- the instructor 203 includes a function to instruct the user device UE whether to calculate P CMAX _ L and P CMAX _ H according to predetermined formulas using a subframe of a CC with a long TTI length as a reference subframe (i.e., calculating P CMAX _ L and P CMAX _ H according to the calculation method 1) or to calculate P CMAX _ L and P CMAX _ H according to the predetermined formulas using a subframe of a CC with a short TTI length as the reference subframe (i.e., calculating P CMAX _ L and P CMAX _ H according to the calculation method 2).
- the instructor 203 may be configured to instruct the user device UE, at a predetermined timing, to select one of the subframe of the CC with the long TTI length (i.e., calculating P CMAX _ L and P CMAX _ H according to the calculation method 1) and the subframe of the CC with the short TTI length (i.e., calculating P CMAX _ L and P CMAX _ H according to the calculation method 2) as the reference subframe.
- the predetermined timing may be determined according to the criteria described in “SWITCHING BETWEEN CALCULATION METHOD 1 AND CALCULATION METHOD 2”.
- each of the user device UE and the base station eNB described above may be implemented by a hardware circuit(s) (e.g., one or more IC chips).
- a part of the functional configuration may be implemented by a hardware circuit(s) and the remaining part of the functional configuration may be implemented by a CPU and programs.
- FIG. 13 is a drawing illustrating an example of a hardware configuration of a user device according to an embodiment.
- FIG. 13 illustrates a configuration that is closer than FIG. 11 to an actual implementation.
- the user device UE includes a radio frequency (RF) module 301 that performs processes related to radio signals, a baseband (BB) processing module 302 that performs baseband signal processing, and a UE control module 303 that performs processes in upper layers.
- RF radio frequency
- BB baseband
- UE control module 303 that performs processes in upper layers.
- the RF module 301 performs processes such as digital-to-analog (D/A) conversion, modulation, frequency conversion, and power amplification on a digital baseband signal received from the BB processing module 302 to generate a radio signal to be transmitted from an antenna. Also, the RF module 301 performs processes such as frequency conversion, analog-to-digital (A/D) conversion, and demodulation on a received radio signal to generate a digital baseband signal, and inputs the digital baseband signal to the BB processing module 302 .
- the RF module 301 may include, for example, a part of the signal transmitter 101 and a part of the signal receiver 102 in FIG. 11 .
- the BB processing module 302 converts an IP packet into a digital baseband signal and vice versa.
- a digital signal processor (DSP) 312 is a processor that performs signal processing in the BB processing module 302 .
- a memory 322 is used as a work area of the DSP 312 .
- the BB processing module 302 may include, for example, a part of the signal transmitter 101 , a part of the signal receiver 102 , and a part of the calculator 103 in FIG. 11 .
- the UE control module 303 performs protocol processing in the IP layer and processes related to applications.
- a processor 313 performs processes of the UE control module 303 .
- a memory 323 is used as a work area of the processor 313 .
- the UE control module 303 may include, for example, a part of the calculator 103 in FIG. 11 .
- FIG. 14 is a drawing illustrating an example of a hardware configuration of a base station according to an embodiment.
- FIG. 14 illustrates a configuration that is closer than FIG. 12 to an actual implementation.
- the base station eNB includes an RF module 401 that performs processes related to radio signals, a BB processing module 402 that performs baseband signal processing, a device control module 403 that performs processes in upper layers, and a communication IF 404 that is an interface for connection with a network.
- the RF module 401 performs processes such as D/A conversion, modulation, frequency conversion, and power amplification on a digital baseband signal received from the BB processing module 402 to generate a radio signal to be transmitted from an antenna. Also, the RF module 401 performs processes such as frequency conversion, A/D conversion, and demodulation on a received radio signal to generate a digital baseband signal, and inputs the digital baseband signal to the BB processing module 402 .
- the RF module 401 may include, for example, a part of the signal transmitter 201 and a part of the signal receiver 202 in FIG. 12 .
- the BB processing module 402 converts an IP packet into a digital baseband signal and vice versa.
- a DSP 412 is a processor that performs signal processing in the BB processing module 402 .
- a memory 422 is used as a work area of the DSP 412 .
- the BB processing module 402 may include, for example, a part of the signal transmitter 201 , a part of the signal receiver 202 , and a part of the instructor 203 in FIG. 12 .
- the device control module 403 performs protocol processing in the IP layer and operation and maintenance (OAM) processing.
- a processor 413 performs processes of the device control module 403 .
- a memory 423 is used as a work area of the processor 413 .
- a secondary storage 433 is, for example, an HDD and stores various settings for operations of the base station eNB itself.
- the device control module 403 may include, for example, a part of the instructor 203 in FIG. 12 .
- An embodiment of the present invention provides a user device for a radio communication system supporting uplink carrier aggregation.
- the user device includes a transmitter that transmits an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and a calculator that calculates a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe.
- This user device UE provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- the calculator may be configured to combine the subframe of the first component carrier with respective subframes of the second component carrier that are included between a start point and an end point of the subframe of the first component carrier and with respective subframes of the second component carrier that cross one of the start point and the end point of the subframe of the first component carrier, to calculate the lower limit of the maximum transmission power using one of the combinations whose lower limit of the maximum transmission power is smallest, and to calculate the upper limit of the maximum transmission power using one of the combinations whose upper limit of the maximum transmission power is largest.
- This configuration makes the maximum transmission power (P cmax ) constant in each subframe of a CC with a long TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB due to power drop in the same subframe. That is, this configuration makes it possible to prevent degradation in the communication quality of the CC with the long TTI length.
- the calculator may combine the subframe of the second component carrier with respective two subframes of the first component carrier before and after the subframe boundary, calculate the lower limit of the maximum transmission power using one of the combinations whose lower limit of the maximum transmission power is smaller, and calculate the upper limit of the maximum transmission power using one of the combinations whose upper limit of the maximum transmission power is larger; and when the subframe of the second component carrier does not cross the subframe boundary of the first component carrier, the calculator may calculate the lower limit and the upper limit of the maximum transmission power using a combination of the subframe of the second component carrier and a subframe of the first component carrier that includes a start point and an end point of the subframe of the second component carrier.
- This configuration makes the maximum transmission power (P cmax ) constant in each subframe of a CC with a short TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB due to power drop in the same subframe. Also, this configuration makes it possible to prevent the reduction in coverage of the CC with the short TTI length.
- the calculator may be configured to select, based on an instruction from the base station or a downlink communication quality, whether to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the first component carrier as the reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the second component carrier as the reference subframe.
- This configuration enables the user device UE to select one of the calculation method 1 and the calculation method 2 implemented in the user device UE.
- the calculator may be configured to switch, at a predetermined timing, between a method of calculating the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the first component carrier as the reference subframe and a method of calculating the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the second component carrier as the reference subframe.
- the calculator may be configured to report, to the base station, whether the lower limit and the upper limit of the maximum transmission power of the uplink signal is calculated according to the predetermined formulas using the subframe of the first component carrier as the reference subframe or the lower limit and the upper limit of the maximum transmission power of the uplink signal are calculated according to the predetermined formulas using the subframe of the second component carrier as the reference subframe.
- This configuration enables the base station eNB to identify which one of the calculation method 1 and the calculation method 2 is used by the user device UE to calculate P CMAX _ L and P CMAX _ H .
- the base station includes a receiver that receives an uplink signal from a user device, and an instructor that instructs the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier.
- This base station eNB provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- the instructor may be configured to instruct the user device, at a predetermined timing, to switch between using the subframe of the first component carrier as the reference subframe and using the subframe of the second component carrier as the reference subframe.
- the user device UE instead of continuously using one of the calculation method 1 and the calculation method 2, the user device UE can switch between the calculation method 1 and the calculation method 2 at an appropriate timing such as a timing when the communication status of a CC changes.
- Another embodiment of the present invention provides a communication method performed by a user device for a radio communication system supporting uplink carrier aggregation.
- the communication method includes transmitting an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and calculating a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe.
- This communication method provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- the instruction method includes receiving an uplink signal from a user device, and instructing the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier.
- This instruction method provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- Each signal may be a message.
- the instruction signal may be an instruction message
- the report signal may be a report message.
- each apparatus the user device UE, the base station eNB described in the above embodiments may be implemented by executing a program stored in a memory by a CPU (processor) of the apparatus, may be implemented by hardware such as hardware circuits including logic for the above-described processes, or may be implemented by a combination of programs and hardware.
- a CPU processor
- Operations of multiple functional units may be performed by one physical component, and an operation of one functional unit may be performed by multiple physical components.
- the order of steps in sequence charts and flowcharts described in the embodiments may be changed unless they do not become inconsistent.
- functional block diagrams are used to describe the user device UE and the base station eNB, the user device UE and the base station eNB may be implemented by hardware, software, or a combination of them.
- Software to be executed by a processor of the user device UE and software to be executed by a processor of the base station eNB according to the embodiments of the present invention may be stored in any appropriate storage medium such as a random access memory (RAM), a flash memory, a read-only memory (ROM), an EPROM, an EEPROM, a register, a hard disk drive (HDD), a removable disk, a CD-ROM, a database, or a server.
- RAM random access memory
- ROM read-only memory
- EPROM an EPROM
- EEPROM electrically erasable programmable read-only memory
- register a register
- HDD hard disk drive
- removable disk a CD-ROM
- database or a server.
- P CMAX _ L is an example of a lower limit of maximum transmission power
- P CMAX _ H is an example of an upper limit of maximum transmission power
Abstract
Description
- The present invention relates to a user device, a base station, a communication method, and an instruction method.
- A Long Term Evolution (LTE) system employs carrier aggregation (CA) where communications are performed using multiple carriers at the same time and using a predetermined bandwidth (maximum of 20 MHz) as a base unit. A carrier used as a base unit in the carrier aggregation is referred to as a component carrier (CC).
- When CA is performed, a primary cell (PCell) and a secondary cell (SCell) are set for a user device. The PCell is a highly-reliable cell and secures connectivity, and the SCell is a subsidiary cell. The user device primarily connects to the PCell and can add the SCell as necessary. The PCell is substantially the same as an independent cell that supports radio link monitoring (RLM) and semi-persistent scheduling (SPS).
- The SCell is a cell that is set for the user device in addition to the PCell. Addition and removal of the SCell is performed by radio resource control (RRC) signaling. Immediately after the SCell is set for the user device, the SCell is in a deactivated state and becomes able to perform communications (able to perform scheduling) only after being activated. In CA of LTE Rel-10, multiple CCs under the same base station are used.
- On the other hand, Rel-12 defines “dual connectivity” (DC) that performs simultaneous communication using CCs under different base stations to achieve high throughput. That is, in the dual connectivity, the user device performs communications using radio resources of two physically-separate base stations at the same time.
- The dual connectivity is a type of CA, which may also be referred to as “inter-eNB CA”, and uses a master eNB (MeNB) and a secondary eNB (SeNB). Here, CA performed using the same base station is referred to as “intra-eNB CA” to distinguish it from “inter-eNB CA”.
- In DC, a cell group composed of one or more cells under the MeNB is referred to as a master cell group (MCG), and a cell group composed of one or more cells under the SeNB is referred to as a secondary cell group (SCG). Uplink CCs are set in at least one SCell in the SCG, and PUCCH is set in one of the uplink CCs. This SCell is referred to as a primary SCell (PSCell).
- In LTE, to enable reception of an uplink signal with a proper power level, the base station controls the transmission power of the user device (transmission power control (TPC)). More specifically, the user device determines the transmission power based on, for example, maximum transmission power (PcmA) with which the user device can transmit an uplink signal, an estimated value of path loss (PL) of a downlink signal, a signal transmission bandwidth, and a power control command (TPC command) from the base station (Non-Patent Document 1).
- Here, in LTE, an upper limit is set for the maximum transmission power (PCMAX) of each user device to reduce interference. The upper limit of the maximum transmission power is referred to as “PCMAX _ H”. Also to reduce interference, it is specified in LTE that the maximum transmission power is reduced when the transmission bandwidth (the number of RBs allocated for uplink) in each subframe is very large (maximum power reduction: MPR). Further, to meet regional conditions, it is specified that the maximum transmission power is further reduced in a specific band when an instruction is given from the network (additional maximum power reduction: A-MPR). The lower limit of the maximum transmission power according to these specifications is referred to as “PCMAX _ L” (Non-Patent Document 2).
-
- [Non-Patent Document 1] 3GPP TS36.213 V12.6.0 (2015-06)
- [Non-Patent Document 2] 3GPP TS36.101 V13.0.0 (2015-07)
- In LTE, to further increase the system capacity, to further increase the data transfer rate, and to further reduce delays in the wireless section, the fifth-generation (5G) radio communication technologies are being considered. In 5G, to achieve a low delay, it is being considered to make the TTI length, which is a minimum unit of scheduling, shorter than the TTI length (1 ms) in LTE. Accordingly, there is a possibility that CA is performed using a combination of cells (CCs) with different TTI lengths.
- Also, at the initial stage of the introduction of 5G, it is expected that instead of operating a 5G radio communication system alone, an LTE radio communication system is operated in combination with the 5G radio communication system. For this reason, there is also a possibility that CA is performed using CCs in LTE and 5G with different TTI lengths.
- However, no method is specified in the current LTE to calculate “PCMAX _ L” and “PCMAX _ H” when CA is performed between cells (CCs) with different TTI lengths. Also, the calculation methods of “PCMAX _ L” and “PCMAX _ H” specified in Non-Patent
Document 2 are based on an assumption that the subframe lengths of CCs are the same (i.e., the TTI lengths are the same), and cannot be applied to a case where CA is performed between cells (CCs) with different TTI lengths. - One object of this disclosure is to solve or reduce the above-described problems, and to provide a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- An aspect of this disclosure provides a user device for a radio communication system that supports uplink carrier aggregation. The user device includes a transmitter that transmits an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and a calculator that calculates a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe.
- Another aspect of this disclosure provides a base station for a radio communication system supporting uplink carrier aggregation. The base station includes a receiver that receives an uplink signal from a user device, and an instructor that instructs the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier.
- An aspect of this disclosure provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
-
FIG. 1 is a drawing used to describe calculation methods of PCMAX _ L in UL CA and sync DC; -
FIG. 2 is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in async DC; -
FIG. 3 is a drawing illustrating an example of a configuration of a radio communication system according to an embodiment; -
FIG. 4A is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated; -
FIG. 4B is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated; -
FIG. 5A is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different and variable TTI lengths are aggregated; -
FIG. 5B is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different and variable TTI lengths are aggregated; -
FIG. 6 is a sequence chart illustrating a process performed by a radio communication system according to an embodiment; -
FIG. 7 is a drawing illustrating a process of switching calculation methods; -
FIG. 8 is a drawing used to describe calculation methods (variation 1) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated; -
FIG. 9 is a drawing used to describe calculation methods (variation 2) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated; -
FIG. 10 is a drawing used to describe calculation methods (variation 3) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated; -
FIG. 11 is a drawing illustrating an example of a functional configuration of a user device according to an embodiment; -
FIG. 12 is a drawing illustrating an example of a functional configuration of a base station according to an embodiment; -
FIG. 13 is a drawing illustrating an example of a hardware configuration of a user device according to an embodiment; and -
FIG. 14 is a drawing illustrating an example of a hardware configuration of a base station according to an embodiment. - Embodiments of the present invention are described below with reference to the accompanying drawings. Embodiments described below are examples, and the present invention is not limited to those embodiments. For example, although it is assumed that a radio communication system according to the embodiments conforms to LTE, the present invention is not limited to LTE and may also be applied to other types of systems. In the specification and the claims of the present application, “LTE” is used in a broad sense and may indicate not only a communication system corresponding to 3GPP release 8 or 9, but also a fifth-generation communication system corresponding to
3GPP release - In the descriptions below, it is assumed that the TTI length is the same as the subframe length. However, the embodiments of the present invention may also be applied to a radio communication system where the TTI length is different from the subframe length. The embodiments of the present invention may be applied to a radio communication system where the TTI length is different from the subframe length by replacing “TTI length” in the descriptions below with “subframe length”.
- As indicated by formula (1) below,
Non-Patent Document 2 specifies that the maximum transmission power (PCMAX) of each user device is a value that falls within a range between PCMAX _ L and PCMAX _ H.Non-Patent Document 2 also specifies that PCMAX _ L and PCMAX _ H of a user device are calculated, respectively, by formula (2) and formula (3) below. A serving cell in formula (2) and formula (3) indicates an uplink CC used for communication. -
-
- PEMAX,c: True value of P-Max specified by network for serving cell (c)
- PPowerClass: Nominal maximum output power (power not including tolerance)
- mprc: True value of maximum power reduction (MPR) at serving cell (c)
- a-mprc: True value of additional maximum power reduction (A-MPR) at serving cell (c)
- pmprc: True value of power management maximum power reduction (P-MPR) at serving cell (c)
- ΔtC,c: One of values 1.41 and 1 determined by specific condition at serving cell (c)
- ΔtIB,c: True value of additional tolerance at serving cell (c)
-
- As indicated by formula (2), “PCMAX _ L” is obtained by calculating power levels for respective CCs (by using a formula corresponding to “calculated for each serving cell (c)” in formula (2)), and selecting a smaller one of a sum (E) of the calculated power levels of CCs and Ppowerclass. According to formula (2), the upper limit of “PCMAX _ L” is Ppowerclass. Also, as indicated by formula (3), “PCMAX _ H” is obtained by selecting a smaller one of a sum of the values of P-Max specified by the network for respective CCs and Ppowerclass. According to formula (3), the upper limit of “PCMAX _ H” is Ppowerclass.
- In the descriptions below, “PCMAX _ L(x,y)” indicates PCMAX _ L that is calculated by pairing a subframe x of a specific CC and a subframe y of another CC different from the specific CC. In other words, PCMAX _ L(x,y) indicates a smaller one of a sum of a power level calculated from various parameters of the subframe x (e.g., PEMAX,c, mprc) and a power level calculated from various parameters of the subframe y (e.g., PEMAX,c, mprc) and Ppowerclass. Similarly, “PCMAX _ H(x,y)” indicates PCMAX _ H that is calculated by pairing a subframe x of a specific CC and a subframe y of another CC different from the specific CC. In other words, PCMAX _ H (x,y) indicates a smaller one of a sum of PEMAX in the subframe x and PEMAX in the subframe y and Ppowerclass.
-
FIG. 1 is a drawing used to describe calculation methods of PCMAX _ L in UL CA and sync DC. FIG. 1 (a 1) illustrates a state where subframes are synchronized in uplink CA usingCC# 1 andCC# 2. In the state where the subframes ofCC# 1 andCC# 2 are synchronized, “PCMAX _ L” in respective subframes can be expressed as PCMAX _ L(i,i) and PCMAX _ L (i+1,i+1). - On the other hand, when different timing advances (TA) are applied to the CCs, the subframes of
CC# 1 and the subframes ofCC# 2 may become slightly out of sync with each other. In this case, as illustrated byFIG. 1 (a 2),Non-Patent Document 2 specifies that in a portion where a subframe i and a subframe i+1 overlap each other, a smaller one of PCMAX _ L(i,i) in the subframe i and PCMAX _ L(i+1,i+1) in the subframe i+i is selected as PCMAX _ L. - Each of
FIG. 1 (b 1) andFIG. 1 (b 2) illustrates a calculation method of “PCMAX _ L” in sync DC. The sync DC is a type of DC that is operated such that the boundaries of subframes of CCs constituting MCG and SCG are almost aligned with each other.FIG. 1 (b 1) illustrates a state where the subframes ofCC# 1 andCC# 2 are synchronized with each other. In the case ofFIG. 1 (b 1), “PCMAX _ L” in respective subframes can be expressed as PCMAX _ L(p,q) and PCMAX _ L(p+1,q+1) Also in the sync DC, as illustrated byFIG. 1 (b 2), there is a case where different timing advances (TA) are applied to the CCs, and the subframes ofCC# 1 and the subframes ofCC# 2 become slightly out of sync with each other. Also in this case,Non-Patent Document 2 specifies that in a portion where the subframes overlap each other, a smaller one of PCMAX _ L(p,q) and PCMAX _ L(p+1, q+1) is selected as PCMAX _ L. -
FIG. 2 is a drawing used to describe calculation methods of PCMAX _ L and PCMAX _ H in async DC. The async DC is a type of DC that is operated such that the boundaries of subframes of CCs constituting MCG and SCG are greatly misaligned with each other. For the async DC,Non-Patent Document 2 specifies different calculation methods of “PCMAX _ L” and “PCMAX _ H” for a case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG and a case where the subframe of the CC in SCG is ahead of the subframe of the CC in MCG. Here, the case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG indicates that the difference between the start point of the subframe of the CC in MCG and the start point of the subframe of the CC in SCG (the SCG subframe that is behind the MCG subframe) is less than or equal to 0.5 ms. -
FIG. 2 (a) illustrates calculation methods for the case where the subframe of the CC in MCG is ahead of the subframe of the CC in SCG.Non-Patent Document 2 specifies that when the subframe of the CC in MCG is ahead of the subframe of the CC in SCG, an MCG subframe is set as a reference subframe, and a smaller one of two values of “PCMAX _ L” obtained by pairing the reference subframe with each of two SCG subframes overlapping the reference subframe is selected as “PCMAX _ L”. Similarly,Non-Patent Document 2 specifies that a larger one of two values of “PCMAX _ H” obtained by pairing the reference subframe with each of two SCG subframes overlapping the reference subframe is selected as “PCMAX _ H”. Specifically, as illustrated inFIG. 2 (a) , a smaller one of PCMAX _ L (p,q) and PCMAX _ L(p,q−1) is selected as “PCMAX _ L” for the period of the subframe p, and a larger one of PCMAX _ H(p,q) and PCMAX _ H(p,q−1) is selected as “PCMAX _ H” for the period of the subframe p. Also for other subframes ( . . . , p−1, p+1, P+2, . . . ), “PCMAX _ L” and “PCMAX _ H” are calculated according to the same methods. -
FIG. 2 (b) illustrates calculation methods for the case where the subframe of the CC in SCG is ahead of the subframe of the CC in MCG. In the case ofFIG. 2 (b) , an SCG subframe is set as a reference subframe, and “PCMAX _ L” and “PCMAX _ H” are calculated according to methods similar to those ofFIG. 2 (a) . -
FIG. 3 is a drawing illustrating an example of a configuration of a radio communication system according to an embodiment. The radio communication system of the present embodiment includes a user device UE, a base station eNBa forming a cell “a”, and a base station eNBb forming a cell “b”. In the descriptions below, the base station eNBa and the base station eNBb may be collectively referred to as a “base station eNB” when distinction is not necessary. - Although
FIG. 3 includes only one user device UE, the radio communication system may include multiple user devices UE. Also, althoughFIG. 3 includes the base station eNBa and the base station eNBb, the radio communication system may include one base station eNB or three or more base stations eNB. Also inFIG. 3 , although the base station eNBa forms the cell “a” and the base station eNBb forms the cell “b”, each of the base station eNBa and the base station eNBb may form multiple cells. Also, the base station eNBa and the base station eNBb may be an MeNB and an SeNB or an SeNB and an MeNB, respectively. CA in the present embodiment may be intra-eNB CA, inter-eNB CA, or a combination of intra-eNB CA and inter-eNB CA. - In the present embodiment, it is assumed that each of the cell “a” and the cell “b” includes a downlink CC and an uplink CC. However, each of the cell “a” and the cell “b” may include only an uplink CC. It is also assumed that the TTI length of the uplink CC of the cell “a” is different from the TTI length of the uplink CC of the cell “b”. For example, the cell “a” may be a 4G (LTE) cell (TTI=1 ms), and the cell “b” may be a 5G cell (e.g., TTI=0.2 ms). Also, both of the cell “a” and the cell “b” may be 5G cells.
- Also in the present embodiment, it is assumed that the user device UE performs uplink CA between a CC of the cell “a” and a CC of the cell “b”. However, the user device UE may also be configured to perform uplink CA by aggregating three or more CCs. Also in the present embodiment, the communication scheme for the uplink CC may be Single-Carrier Frequency-Division Multiple Access (SC-FDMA) as in LTE, orthogonal frequency-division multiplexing (OFDM), or any other communication scheme.
- <Calculations of “PCMAX _ L” and “PCMAX _ H”>
- The user device UE of the present embodiment may be configured to define each subframe of a CC with a long TTI length as a reference subframe, and to calculate “PCMAX _ L” and “PCMAX _ H” using formulas (2) and (3) described above. In the descriptions below, a method where each subframe of a CC with a long TTI length is defined as a reference subframe and “PCMAX _ L” and “PCMAX _ H” are calculated using formulas (2) and (3) described above is referred to as a “
calculation method 1”. - More specifically, the user device UE combines the reference subframe of the CC having the long TTI length with respective subframes of a CC having a short TTI length that are included between the start point and the end point of the reference subframe and with respective subframes of the CC having the short TTI length that cross one of the start point and the end point of the reference subframe, and calculates “PCMAX _ L” for the period of the reference subframe by selecting the smallest “PCMAX _ L” from “PCMAX _ L” values calculated for the respective combinations. Similarly, the user device UE calculates “PCMAX _ H” for the period of the reference subframe by selecting the largest “PCMAX _ H” from “PCMAX _ H” values calculated for the respective combinations.
-
FIGS. 4A and 4B are drawings used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated. An example is described with reference toFIG. 4A . The user device UE selects the smallest one of PCMAX _ L(p,q−1), PCMAX _ L(p,q), PCMAX _ L(p,q+1), and PCMAX _ L(p,q+n) as “PCMAX _ L” for the period of the subframe p (reference subframe). Similarly, the user device UE selects the largest one of PCMAX _ H(p,q−1), PCMAX _ H(p,q) PCMAX _ H(p,q+1), and PCMAX _ H(p,q+n) as “PCMAX _ H” for the period of the subframe p. The user device UE can continuously calculate “PCMAX _ L” and “PCMAX _ H” while performing uplink communications by performing this process for each subframe ofCC# 1. - Calculating “PCMAX _ L” and “PCMAX _ H” with the
calculation method 1 makes the maximum transmission power (PCMAX) constant in each subframe of the CC with the long TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB providing the CC with the long TTI length due to power drop in the same subframe. That is, using thecalculation method 1 makes it possible to prevent degradation in the communication quality of the CC with the long TTI length. - The user device UE of the present embodiment may also be configured to define each subframe of the CC with the short TTI length as a reference subframe, and to calculate “PCMAX _ L” and “PCMAX _ H” using formulas (2) and (3) described above. In the descriptions below, a method where each subframe of the CC with the short TTI length is defined as a reference subframe and “PCMAX _ L” and “PCMAX _ H” are calculated using formulas (2) and (3) described above is referred to as a “
calculation method 2”. - Specifically, when the reference subframe of the CC with the short TTI length crosses a subframe boundary of the CC with the long TTI length, the user device UE calculates “PCMAX _ L” for the period of the reference subframe by selecting the smaller “PCMAX _ L” from “PCMAX _ L” values calculated for the combinations of the reference subframe and respective two subframes of the CC with the long TTI length that are located before and after the subframe boundary. Similarly, the user device UE calculates “PCMAX _ H” for the period of the reference subframe by selecting the larger “PCMAX _ H” from “PCMAX _ H” values calculated for the respective combinations.
- Also, when the reference subframe of the CC with the short TTI length does not cross any subframe boundary of the CC with the long TTI length, the user device UE calculates “PCMAX _ L” and “PCMAX _ H” by using the combination of the reference subframe and a subframe of the CC with the long TTI length that includes the start point and the end point of the reference subframe.
- An example is described with reference to
FIG. 4B . In the example ofFIG. 4B , a subframe q−1 crosses the boundary between a subframe p−1 and a subframe p. In this case, the user device UE selects the smaller one of PCMAX _ L (p−1,q−1) and PCMAX _ L(p,q−1) as “PCMAX _ L” for the period of the subframe q−1 (reference subframe). Similarly, the user device UE selects the larger one of PCMAX _ H(p−1,q−1) and PCMAX _ H(p,q−1) as “PCMAX _ H” for the period of the subframe q−1. The user device UE also calculates “PCMAX _ L” and “PCMAX _ H” for a subframe q+n (reference subframe) crossing the boundary between the subframe p and a subframe p+1 in a similar manner. - In the example of
FIG. 4B , a subframe q does not cross any subframe boundary of CC#1 (i.e., the subframe q is included in the period of the subframe p). In this case, the user device UE uses PCMAX _ L(p,q) and PCMAX _ H(p,q) as “PCMAX _ L” and “PCMAX _ H” for the period of the subframe q (reference subframe). The user device UE also calculates “PCMAX _ L” and “PCMAX _ H” for a subframe q+1 that does not cross any subframe boundary ofCC# 1 in a similar manner. The user device UE can continuously calculate “PCMAX _ L” and “PCMAX _ H” while performing uplink communications by performing this process for each subframe ofCC# 2. - Calculating “PCMAX _ L” and “PCMAX _ H” with the
calculation method 2 makes the maximum transmission power (PCMAX) constant in each subframe of the CC with the short TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB providing the CC with the short TTI length due to power drop in the same subframe. Here, using thecalculation method 1 has an advantage of making “PCMAX _ L” constant in each subframe of the CC with the long TTI length. However, with thecalculation method 1, there is a risk, for example, that the maximum transmission power is set at an unnecessarily low value for some of subframes of the CC with the short TTI length that overlap the subframe of the CC with the long TTI length, and the coverage of an area corresponding to the CC with the short TTI length is reduced. Using thecalculation method 2 does not cause such a problem and makes it possible to prevent the reduction in area coverage. That is, using thecalculation method 2 makes it possible to prevent degradation in the communication quality of the CC with the short TTI length. - Similarly to the related art, even when PCMAX _ L and PCMAX _ H are calculated using the
calculation method 1 or thecalculation method 2, the maximum transmission power (PCMAX) of each user device is set at a value within a range between PCMAX _ L and PCMAX _ H. -
FIGS. 5A and 5B are drawings used to describe calculation methods of PCMAX _ L and PCMAX _ H in a case where CCs with different and variable TTI lengths are aggregated.FIGS. 5A and 5B illustrate a case where the TTI length (subframe length) ofCC# 2 is variable and the TTI length of the subframe q is different from that inFIGS. 4A and 4B . - Even when CCs with a variable TTI length are aggregated, the user device UE may calculate “PCMAX _ L” and “PCMAX _ H” using one of the
calculation method 1 and thecalculation method 2. Calculation methods of “PCMAX _ L” and “PCMAX _ H” for each subframe inFIGS. 5A and 5B are substantially the same as those described with reference toFIGS. 4A and 4B , and therefore their descriptions are omitted here. - In the present embodiment, the user device UE may be configured to always use the calculation method 1 (i.e., to set a subframe of the CC with the long TTI length as a reference frame) to calculate “PCMAX _ L” and “PCMAX _ H”, or to always use the calculation method 2 (i.e., to set a subframe of the CC with the short TTI length as a reference frame) to calculate “PCMAX _ L” and “PCMAX _ H” Also, the user device UE may be configured to select whether to use the
calculation method 1 or thecalculation method 2 to calculate “PCMAX _ L” and “PCMAX _ H” according to an instruction from the base station eNB. - For example, as illustrated by
FIG. 6 (a) , the user device UE may be configured to calculate “PCMAX _ L” and “PCMAX _ H” using thecalculation method 1 when an instruction signal (S11) from the base station eNB includes information indicating thecalculation method 1, and to calculate “PCMAX _ L” and “PCMAX _ H” using thecalculation method 2 when the instruction signal includes information indicating thecalculation method 2. The instruction signal may be a physical layer (PHY) signal, a MAC layer signal, or an RRC signal. Also, the instruction signal may be transmitted from either one of the LTE (4G) base station eNB and the 5G base station eNB. Also, when instruction signals are received from both of the LTE (4G) base station eNB and the 5G base station eNB, the user device UE may be configured to give priority to the instruction signal from the LTE (4G) base station eNB (i.e., follow the instruction signal from the LTE (4G) base station eNB), or to give priority to the instruction signal from the 5G base station eNB (i.e., follow the instruction signal from the 5G base station eNB). - The base station eNB may be configured to instruct the user device UE whether to use the
calculation method 1 or thecalculation method 2 based on the communication quality (e.g., reference signal received quality (RSRQ), reference signal received power (RSRP), or channel quality indicator (CQI)) of each CC (the downlink CC of each cell constituting CA) reported from the user device UE. - Also, the user device UE may be configured to select by itself whether to use the
calculation method 1 or thecalculation method 2 to calculate “PCMAX _ L” and “PCMAX _ H”. - For example, the user device UE may be configured to measure and compare the communication quality levels (e.g., RSRQ, RSRP, or CQI) of downlink CCs of cells (downlink CCs of the same cells as those providing uplink CCs to be aggregated) to select whether to use the
first calculation method 1 or thesecond calculation method 2. - Also, the user device UE may be configured to report to the base station eNB whether the
calculation method 1 or thecalculation method 2 has been used. For example, as illustrated byFIG. 6 (b) , the user device UE may be configured to transmit, to the base station eNB, a report signal (S21) including information indicating whether thecalculation method 1 or thecalculation method 2 has been used. The report signal may be a physical layer (PHY) signal, a MAC layer signal, or an RRC signal. - In the present embodiment, the user device UE may be configured to switch between the
calculation method 1 and thecalculation method 2 to calculate “PCMAX _ L” and “PCMAX _ H” at a predetermined timing.FIG. 7 is a drawing illustrating a process of switching calculation methods. In the example ofFIG. 7 , the calculation methods are switched at the timing of each of step S51 and step S52. - The user device UE may be configured to switch the calculation methods according to an instruction from the base station eNB or based on its own decision. When the calculation methods are switched according to an instruction from the base station eNB, the base station eNB may transmit an instruction signal (S11 in
FIG. 6 (a)) to the user device UE, and the user device UE may switch the calculation methods at a timing when the instruction signal is received. Also, the timing when the user device UE switches the calculation methods may be at a subframe boundary of the CC with the short (or long) TTI length, or may be after a predetermined period of time from the timing when the user device UE decides to switch the calculation methods (or the timing when an instruction to switch the calculation methods is received from the base station eNB). Also, the calculation methods may be switched at any other appropriate timing. - Examples of criteria used by the base station eNB or the user device UE to switch the calculation methods are described below.
- The user device UE or the base station eNB may be configured to switch (or instruct to switch) the calculation methods depending on whether priority is given to the communication quality of the CC with the long TTI length or the communication quality of the CC with the short TTI length. For example, the user device UE or the base station eNB may be configured to compare the amounts of data to be transmitted using respective uplink CCs and to switch (or instruct to switch) the calculation methods such that priority is given to the communication quality of one of the CCs with which a larger amount of data is to be transmitted. Also, the user device UE or the base station eNB may be configured to switch (or instruct to switch) the calculation methods such that priority is given to the communication quality of a CC for which a high-priority bearer (e.g., a bearer with a small QoS class identifier (QCI)) is set.
- The user device UE or the base station eNB may be configured to switch (or instruct to switch) to the
calculation method 1 at a timing when the communication quality of the CC with the long TTI length becomes good and to switch (or instruct to switch) to thecalculation method 2 at a timing when the communication quality of the CC with the short TTI length becomes good, based on the communication quality levels (e.g., RSRQ, RSRP, or CQI) of the CCs. Alternatively, the user device UE or the base station eNB may be configured to switch (or instruct to switch) to thecalculation method 2 at a timing when the communication quality of the CC with the long TTI length becomes good and to switch (or instruct to switch) to thecalculation method 1 at a timing when the communication quality of the CC with the short TTI length becomes good. - The user device UE or the base station eNB may be configured to switch (or instruct to switch) to the
calculation method 1 at a timing when the CC with the long TTI length is attached to MCG and to switch (or instruct to switch) to thecalculation method 2 at a timing when the CC with the short TTI length is attached to MCG. Alternatively, the user device UE or the base station eNB may be configured to switch (or instruct to switch) to thecalculation method 2 at a timing when the CC with the long TTI length is attached to MCG and to switch (or instruct to switch) to thecalculation method 1 at a timing when the CC with the short TTI length is attached to MCG. Here, one of two cell groups (CGs) including a PCell is MCG and another one of the CGs including no PCell is SCG. Thus, that the CC with the long (or short) TTI length is attached to MCG indicates a case where a CG including the PCell changes to another CG due to, for example, handover. - The user device UE or the base station eNB may be configured to switch (or to instruct to switch) between the
calculation method 1 and thecalculation method 2 based on operational states of CCs. - For example, while the
calculation method 1 is being used (i.e., while the reference frame is set in the CC with the long TTI length), the user device UE or the base station eNB may be configured to switch (or to instruct to switch) to thecalculation method 2 when the CC with the long TTI length is deactivated, the TA timer of the CC is stopped, uplink transmission (e.g., SRS, PUCCH, or PUSCH) with the CC is not being performed, the CC transitions to a DRX state, or the CC transitions to a measurement gap state. - Similarly, while the
calculation method 2 is being used (i.e., while the reference frame is set in the CC with the short TTI length), the user device UE or the base station eNB may be configured to switch (or to instruct to switch) to thecalculation method 1 when the CC with the short TTI length is deactivated, the TA timer of the CC is stopped, uplink transmission (e.g., SRS, PUCCH, or PUSCH) with the CC is not being performed, the CC transitions to a DRX state, or the CC transitions to a measurement gap state. - <Calculations of “PCMAX _ L” and “PCMAX _ H” (Variations)>
- When CA is performed using three or more CCs, the user device UE may be configured to calculate “PCMAX _ L” and “PCMAX _ H” using a combination of the
calculation method 1, thecalculation method 2, and the related-art calculation method. Variations of calculation methods are described below. -
FIG. 8 is a drawing used to describe a calculation method (variation 1) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated. In the example ofFIG. 8 , uplink CA is performed usingCC# 1 andCC# 2 belonging to MCG andCC# 3 andCC# 4 belonging to SCG. - In the example of
FIG. 8 , the subframe intervals ofCC# 1 andCC# 2 are the same, and the subframes ofCC# 1 andCC# 2 are synchronized with each other. Also, the subframe intervals ofCC# 3 andCC# 4 are the same, and the subframes ofCC# 3 andCC# 4 are synchronized with each other. On the other hand, the subframe interval (TTI length) ofCC# 1 andCC# 2 is different from the subframe interval (TTI length) ofCC# 3 andCC# 4. - When CA is performed as illustrated by
FIG. 8 , PCMAX _ L and PCMAX _ H are first calculated for the combinations of subframes ofCC# 1 andCC# 2 using the related-art calculation method (the calculation method ofFIG. 1 (a 1) orFIG. 1 (b 1)), and the calculated PCMAX _ L and PCMAX _ H are set as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. - Similarly, PCMAX _ L and PCMAX _ H are calculated for the combinations of subframes of
CC# 3 andCC# 4 using the related-art calculation method (the calculation method ofFIG. 1 (a 1) orFIG. 1 (b 1)), and the calculated PCMAX _ L and PCMAX _ H are set as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 3. - Next, using the tentative PCMAX _ L and PCMAX _ H, PCMAX _ L and PCMAX _ H are calculated for the combinations of subframes of
CC# 2 andCC# 3 according to thecalculation method 1 or thecalculation method 2. - When PCMAX _ L and PCMAX _ H are calculated using the
calculation method 1 or thecalculation method 2 in each of the variations, the tentative “PCMAX _ L” of each subframe and the tentative “PCMAX _ H” of each subframe are used to calculate PCMAX _ L and PCMAX _ H for each combination of subframes. - As an example, assume a case where PCMAX _ L is obtained for a combination of tentative “PCMAX _ L” of a subframe x of
CC# 2 and tentative “PCMAX _ L” of a subframe y ofCC# 3. First, the tentative “PCMAX _ L” of a subframe x ofCC# 2 and the tentative “PCMAX _ L” of a subframe y ofCC# 3 are summed. This calculation corresponds to summing (Σ) values “calculated for each serving cell (c)” in formula (2). Next, when the sum is less than Ppowerclass, the sum is used as PCMAX _ L; and when the sum is greater than or equal to Ppowerclass, Ppowerclass is used as PCMAX _ L. This indicates that the upper limit of “PCMAX _ L” is Ppowerclass as in formula (2). PCMAX _ L is calculated through the above process. - Similarly, assume a case where PCMAX _ H is obtained for a combination of tentative “PCMAX _ H” of the subframe x of
CC# 2 and the tentative “PCMAX _ H” of the subframe y ofCC# 3. First, the tentative “PCMAX _ H” of a subframe x ofCC# 2 and the tentative “PCMAX _ H” of the subframe y ofCC# 3 are summed. This calculation corresponds to “calculated for each serving cell (c), and calculated values are totaled” in formula (3). Next, when the sum is less than Ppowerclass, the sum is used as PCMAX _ H; and when the sum is greater than or equal to Ppowerclass, Ppowerclass is used as PCMAX _ H. This indicates that the upper limit of “PCMAX _ H” is Ppowerclass as in formula (3) PCMAX _ H is calculated through the above process. - The above described calculation method of PCMAX _ L is equivalent to a process of calculating PCMAX _ L values of subframes of respective CCs using the part “calculated for each serving cell (c)” of formula (2), summing the calculated PCMAX _ L values of the CCs, using the sum as PCMAX _ L when the sum is less than Ppowerclass, and using Ppowerclass as PCMAX _ L when the sum is greater than or equal to Ppowerclass.
- Similarly, the above described calculation method of PCMAX _ H is equivalent to a process of summing PEMAX values of subframes of respective CCs, using the sum as PCMAX _ H when the sum is less than Ppowerclass, and using Ppowerclass as PCMAX _ H when the sum is greater than or equal to Ppowerclass.
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FIG. 8 (a) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 1, andFIG. 8 (b) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 2. - In the example of
FIG. 8 (a) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 1 andCC# 2 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. The user device UE also calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 3 andCC# 4 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 3. Next, the user device UE sets each subframe ofCC# 2 as a reference subframe, and calculates “PCMAX _ L” and “PCMAX _ H” for the combinations of subframes ofCC# 2 andCC# 3 by using thecalculation method 1. - In the example of
FIG. 8 (b) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 1 andCC# 2 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. The user device UE also calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 3 andCC# 4 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 3. Next, the user device UE sets each subframe ofCC# 3 as a reference subframe, and calculates “PCMAX _ L” and “PCMAX _ H” for the combinations of subframes ofCC# 2 andCC# 3 by using thecalculation method 2. -
FIG. 9 is a drawing used to describe a calculation method (variation 2) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated. In the example ofFIG. 9 , uplink CA is performed usingCC# 1 belonging to MCG andCC# 2 andCC# 3 belonging to SCG. - In the example of
FIG. 9 , the subframe intervals ofCC# 1 andCC# 2 are different from each other, and the subframe intervals ofCC# 2 andCC# 3 are also different from each other. - When CA is performed as illustrated by
FIG. 9 , PCMAX _ L and PCMAX _ H are first calculated for the combinations of subframes ofCC# 2 andCC# 3 using the calculation method 1 (using each subframe ofCC# 2 as a reference subframe), and the calculated PCMAX _ L and PCMAX _ H are set as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. - Next, using the tentative PCMAX _ L and PCMAX _ H, PCMAX _ L and PCMAX _ H are calculated for the combinations of subframes of
CC# 1 andCC# 2 according to thecalculation method 1 or thecalculation method 2. -
FIG. 9 (a) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 1, andFIG. 9 (b) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 2. - In the example of
FIG. 9 (a) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 2 andCC# 3 using thecalculation method 1, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. Next, the user device UE sets each subframe ofCC# 1 as a reference subframe, and calculates “PCMAX _ L” and “PCMAX _ H” for the combinations of subframes ofCC# 1 andCC# 2 by using thecalculation method 1. - In the example of
FIG. 9 (b) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 2 andCC# 3 using thecalculation method 1, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. Next, the user device UE sets each subframe ofCC# 2 as a reference subframe, and calculates “PCMAX _ L” and “PCMAX _ H” for the combinations of subframes ofCC# 1 andCC# 2 by using thecalculation method 2. -
FIG. 10 is a drawing used to describe a calculation method (variation 3) of PCMAX _ L and PCMAX _ H in a case where CCs with different TTI lengths are aggregated. In the example ofFIG. 10 , uplink CA is performed usingCC# 1 belonging to MCG andCC# 2 andCC# 3 belonging to SCG. - In the example of
FIG. 10 , the subframe intervals ofCC# 2 andCC# 3 are the same, but the subframes ofCC# 2 andCC# 3 are not synchronized with each other. Also, the subframe intervals ofCC# 1 andCC# 2 are different from each other. - When CA is performed as illustrated by
FIG. 10 , PCMAX _ L and PCMAX _ H are first calculated for the combinations of subframes ofCC# 2 andCC# 3 using the related-art calculation method (the calculation method ofFIG. 2 (a) ), and the calculated PCMAX _ L and PCMAX _ H are set as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. - Next, using the tentative PCMAX _ L and PCMAX _ H, PCMAX _ L and PCMAX _ H are calculated for the combinations of subframes of
CC# 1 andCC# 2 according to thecalculation method 1 or thecalculation method 2. -
FIG. 10 (a) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 1, andFIG. 10 (b) illustrates a case where PCMAX _ L and PCMAX _ H are calculated using thecalculation method 2. - In the example of
FIG. 10 (a) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 2 andCC# 3 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. Next, the user device UE sets each subframe ofCC# 1 as a reference subframe, and calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 1 andCC# 2 by using thecalculation method 1. - In the example of
FIG. 10 (b) , the user device UE calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 2 andCC# 3 using the related-art calculation method, and sets the calculated PCMAX _ L and PCMAX _ H as tentative PCMAX _ L and PCMAX _ H for the subframes ofCC# 2. Next, the user device UE sets each subframe ofCC# 2 as a reference subframe, and calculates PCMAX _ L and PCMAX _ H for the combinations of subframes ofCC# 1 andCC# 2 by using thecalculation method 2. - As still another variation, the user device UE may be configured to handle multiple consecutive subframes as one reference subframe in the
calculation method 2. For example, in the example ofFIG. 4B , the user device UE may handle two consecutive subframes (p and p+1) as one reference subframe. Because there may be cases where the values of PCMAX _ L and PCMAX _ H do not frequently change, this method makes it possible to reduce the processing load of the user device UE. - Variations of the calculation methods are described above. According to the embodiments of the present invention, it is possible to calculate “PCMAX _ L” and “PCMAX _ H” regardless of how CCs are combined in CA by combining the
calculation method 1, thecalculation method 2, and the related-art calculation method. - Examples of functional configurations of the user device UE and the base station eNB that perform the methods of the above embodiments are described below.
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FIG. 11 is a drawing illustrating an example of a functional configuration of a user device according to an embodiment. As illustrated byFIG. 11 , the user device UE includes asignal transmitter 101, asignal receiver 102, and acalculator 103.FIG. 11 illustrates only functional components of the user device UE that are particularly relevant to the present embodiment, and the user device UE may also at least include unshown functional components that are necessary for operations conforming to LTE. Also, the functional configuration ofFIG. 11 is just an example. As long as operations related to the present embodiment can be performed, the categorization and the names of the functional components may be freely changed. - The
signal transmitter 101 includes a function to wirelessly transmit various physical layer signals. Thesignal receiver 102 includes a function to wirelessly receive various signals from the base station eNB, and obtain upper layer signals from the received physical layer signals. Each of thesignal transmitter 101 and thesignal receiver 102 includes a function to perform CA communications by aggregating multiple CCs. Also, each of thesignal transmitter 101 and thesignal receiver 102 includes a function to perform CA communications according to DC between MeNB and SeNB. - The
calculator 103 includes a function to calculate PCMAX _ L and PCMAX _ H for an uplink signal according to predetermined formulas using one of a subframe of a CC with a long TTI length and a subframe of a CC with a short TTI length as a reference subframe. - Also, the
calculator 103 may be configured to select, based on an instruction from the base station eNB or downlink communication quality, whether to calculate PCMAX _ L and PCMAX _ H according to the predetermined formulas using the subframe of the CC with the long TTI length as the reference subframe or to calculate PCMAX _ L and PCMAX _ H according to the predetermined formulas using the subframe of the CC with the short TTI length as the reference subframe. - Also, the
calculator 103 may be configured to switch, at a predetermined timing, between a method of calculating PCMAX _ L and PCMAX _ H according to the predetermined formulas using the subframe of the CC with the long TTI length as the reference subframe and a method of calculating PCMAX _ L and PCMAX _ H according to the predetermined formulas using the subframe of the CC with the short TTI length as the reference subframe. The predetermined timing may be determined according to the criteria described in “SWITCHING BETWEENCALCULATION METHOD 1 ANDCALCULATION METHOD 2”. -
FIG. 12 is a drawing illustrating an example of a functional configuration of a base station according to an embodiment. As illustrated byFIG. 12 , the base station eNB includes asignal transmitter 201, asignal receiver 202, and aninstructor 203.FIG. 12 illustrates only functional components of the base station eNB that are particularly relevant to the present embodiment, and the base station eNB may also at least include unshown functional components that are necessary for operations conforming to LTE. Also, the functional configuration ofFIG. 12 is just an example. As long as operations related to the present embodiment can be performed, the categorization and the names of the functional components may be freely changed. - The
signal transmitter 201 includes a function to wirelessly transmit various physical layer signals. Thesignal receiver 202 includes a function to wirelessly receive various signals from the user devices UE, and obtain upper layer signals from the received physical layer signals. Each of thesignal transmitter 201 and thesignal receiver 202 includes a function to perform CA communications by aggregating multiple CCs. - The
instructor 203 includes a function to instruct the user device UE whether to calculate PCMAX _ L and PCMAX _ H according to predetermined formulas using a subframe of a CC with a long TTI length as a reference subframe (i.e., calculating PCMAX _ L and PCMAX _ H according to the calculation method 1) or to calculate PCMAX _ L and PCMAX _ H according to the predetermined formulas using a subframe of a CC with a short TTI length as the reference subframe (i.e., calculating PCMAX _ L and PCMAX _ H according to the calculation method 2). - Also, the
instructor 203 may be configured to instruct the user device UE, at a predetermined timing, to select one of the subframe of the CC with the long TTI length (i.e., calculating PCMAX _ L and PCMAX _ H according to the calculation method 1) and the subframe of the CC with the short TTI length (i.e., calculating PCMAX _ L and PCMAX _ H according to the calculation method 2) as the reference subframe. The predetermined timing may be determined according to the criteria described in “SWITCHING BETWEENCALCULATION METHOD 1 ANDCALCULATION METHOD 2”. - The entire functional configuration of each of the user device UE and the base station eNB described above may be implemented by a hardware circuit(s) (e.g., one or more IC chips). Alternatively, a part of the functional configuration may be implemented by a hardware circuit(s) and the remaining part of the functional configuration may be implemented by a CPU and programs.
-
FIG. 13 is a drawing illustrating an example of a hardware configuration of a user device according to an embodiment.FIG. 13 illustrates a configuration that is closer thanFIG. 11 to an actual implementation. As illustrated byFIG. 13 , the user device UE includes a radio frequency (RF)module 301 that performs processes related to radio signals, a baseband (BB)processing module 302 that performs baseband signal processing, and aUE control module 303 that performs processes in upper layers. - The
RF module 301 performs processes such as digital-to-analog (D/A) conversion, modulation, frequency conversion, and power amplification on a digital baseband signal received from theBB processing module 302 to generate a radio signal to be transmitted from an antenna. Also, theRF module 301 performs processes such as frequency conversion, analog-to-digital (A/D) conversion, and demodulation on a received radio signal to generate a digital baseband signal, and inputs the digital baseband signal to theBB processing module 302. TheRF module 301 may include, for example, a part of thesignal transmitter 101 and a part of thesignal receiver 102 inFIG. 11 . - The
BB processing module 302 converts an IP packet into a digital baseband signal and vice versa. A digital signal processor (DSP) 312 is a processor that performs signal processing in theBB processing module 302. Amemory 322 is used as a work area of theDSP 312. TheBB processing module 302 may include, for example, a part of thesignal transmitter 101, a part of thesignal receiver 102, and a part of thecalculator 103 inFIG. 11 . - The
UE control module 303 performs protocol processing in the IP layer and processes related to applications. Aprocessor 313 performs processes of theUE control module 303. Amemory 323 is used as a work area of theprocessor 313. TheUE control module 303 may include, for example, a part of thecalculator 103 inFIG. 11 . -
FIG. 14 is a drawing illustrating an example of a hardware configuration of a base station according to an embodiment.FIG. 14 illustrates a configuration that is closer thanFIG. 12 to an actual implementation. As illustrated byFIG. 14 , the base station eNB includes anRF module 401 that performs processes related to radio signals, aBB processing module 402 that performs baseband signal processing, adevice control module 403 that performs processes in upper layers, and a communication IF 404 that is an interface for connection with a network. - The
RF module 401 performs processes such as D/A conversion, modulation, frequency conversion, and power amplification on a digital baseband signal received from theBB processing module 402 to generate a radio signal to be transmitted from an antenna. Also, theRF module 401 performs processes such as frequency conversion, A/D conversion, and demodulation on a received radio signal to generate a digital baseband signal, and inputs the digital baseband signal to theBB processing module 402. TheRF module 401 may include, for example, a part of thesignal transmitter 201 and a part of thesignal receiver 202 inFIG. 12 . - The
BB processing module 402 converts an IP packet into a digital baseband signal and vice versa. ADSP 412 is a processor that performs signal processing in theBB processing module 402. Amemory 422 is used as a work area of theDSP 412. TheBB processing module 402 may include, for example, a part of thesignal transmitter 201, a part of thesignal receiver 202, and a part of theinstructor 203 inFIG. 12 . - The
device control module 403 performs protocol processing in the IP layer and operation and maintenance (OAM) processing. Aprocessor 413 performs processes of thedevice control module 403. Amemory 423 is used as a work area of theprocessor 413. Asecondary storage 433 is, for example, an HDD and stores various settings for operations of the base station eNB itself. Thedevice control module 403 may include, for example, a part of theinstructor 203 inFIG. 12 . - An embodiment of the present invention provides a user device for a radio communication system supporting uplink carrier aggregation. The user device includes a transmitter that transmits an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and a calculator that calculates a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe. This user device UE provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- In a case where the lower limit and the upper limit of the maximum transmission power of the uplink signal are calculated according to the predetermined formulas by using the subframe of the first component carrier as the reference subframe, the calculator may be configured to combine the subframe of the first component carrier with respective subframes of the second component carrier that are included between a start point and an end point of the subframe of the first component carrier and with respective subframes of the second component carrier that cross one of the start point and the end point of the subframe of the first component carrier, to calculate the lower limit of the maximum transmission power using one of the combinations whose lower limit of the maximum transmission power is smallest, and to calculate the upper limit of the maximum transmission power using one of the combinations whose upper limit of the maximum transmission power is largest. This configuration makes the maximum transmission power (Pcmax) constant in each subframe of a CC with a long TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB due to power drop in the same subframe. That is, this configuration makes it possible to prevent degradation in the communication quality of the CC with the long TTI length.
- In a case where the lower limit and the upper limit of the maximum transmission power are calculated for each subframe of the uplink signal according to the predetermined formulas by using the subframe of the second component carrier as the reference subframe, when the subframe of the second component carrier crosses a subframe boundary of the first component carrier, the calculator may combine the subframe of the second component carrier with respective two subframes of the first component carrier before and after the subframe boundary, calculate the lower limit of the maximum transmission power using one of the combinations whose lower limit of the maximum transmission power is smaller, and calculate the upper limit of the maximum transmission power using one of the combinations whose upper limit of the maximum transmission power is larger; and when the subframe of the second component carrier does not cross the subframe boundary of the first component carrier, the calculator may calculate the lower limit and the upper limit of the maximum transmission power using a combination of the subframe of the second component carrier and a subframe of the first component carrier that includes a start point and an end point of the subframe of the second component carrier. This configuration makes the maximum transmission power (Pcmax) constant in each subframe of a CC with a short TTI length, and thereby makes it possible to prevent degradation in the demodulation accuracy at the base station eNB due to power drop in the same subframe. Also, this configuration makes it possible to prevent the reduction in coverage of the CC with the short TTI length.
- The calculator may be configured to select, based on an instruction from the base station or a downlink communication quality, whether to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the first component carrier as the reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the second component carrier as the reference subframe. This configuration enables the user device UE to select one of the
calculation method 1 and thecalculation method 2 implemented in the user device UE. - The calculator may be configured to switch, at a predetermined timing, between a method of calculating the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the first component carrier as the reference subframe and a method of calculating the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using the subframe of the second component carrier as the reference subframe. With this configuration, instead of continuously using one of the
calculation method 1 and thecalculation method 2, the user device UE can switch between thecalculation method 1 and thecalculation method 2 at an appropriate timing such as a timing when the communication status of a CC changes. - The calculator may be configured to report, to the base station, whether the lower limit and the upper limit of the maximum transmission power of the uplink signal is calculated according to the predetermined formulas using the subframe of the first component carrier as the reference subframe or the lower limit and the upper limit of the maximum transmission power of the uplink signal are calculated according to the predetermined formulas using the subframe of the second component carrier as the reference subframe. This configuration enables the base station eNB to identify which one of the
calculation method 1 and thecalculation method 2 is used by the user device UE to calculate PCMAX _ L and PCMAX _ H. - Another embodiment of the present invention provides a base station for a radio communication system supporting uplink carrier aggregation. The base station includes a receiver that receives an uplink signal from a user device, and an instructor that instructs the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier. This base station eNB provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- The instructor may be configured to instruct the user device, at a predetermined timing, to switch between using the subframe of the first component carrier as the reference subframe and using the subframe of the second component carrier as the reference subframe. With this configuration, instead of continuously using one of the
calculation method 1 and thecalculation method 2, the user device UE can switch between thecalculation method 1 and thecalculation method 2 at an appropriate timing such as a timing when the communication status of a CC changes. - Another embodiment of the present invention provides a communication method performed by a user device for a radio communication system supporting uplink carrier aggregation. The communication method includes transmitting an uplink signal to a base station by using a first component carrier and a second component carrier having a TTI length shorter than a TTI length of the first component carrier, and calculating a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using one of a subframe of the first component carrier and a subframe of the second component carrier as a reference subframe. This communication method provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- Another embodiment of the present invention provides an instruction method performed by a base station for a radio communication system supporting uplink carrier aggregation. The instruction method includes receiving an uplink signal from a user device, and instructing the user device whether to calculate a lower limit and an upper limit of a maximum transmission power of the uplink signal according to predetermined formulas using a subframe of a first component carrier as a reference subframe or to calculate the lower limit and the upper limit of the maximum transmission power of the uplink signal according to the predetermined formulas using a subframe of a second component carrier as the reference subframe, the second component carrier having a TTI length shorter than a TTI length of the first component carrier. This instruction method provides a technology that makes it possible to properly calculate the lower limit and the upper limit of the maximum transmission power for communications where CA is performed using CCs with different TTI lengths.
- Each signal may be a message. For example, the instruction signal may be an instruction message, and the report signal may be a report message.
- The order of steps described in each method claim is an example, and the steps may be performed in any other order unless otherwise mentioned.
- Components of each apparatus (the user device UE, the base station eNB) described in the above embodiments may be implemented by executing a program stored in a memory by a CPU (processor) of the apparatus, may be implemented by hardware such as hardware circuits including logic for the above-described processes, or may be implemented by a combination of programs and hardware.
- Embodiments of the present invention are described above. However, the present invention is not limited to the above-described embodiments, and a person skilled in the art may understand that variations, modifications, and replacements may be made to the above embodiments. Although specific values are used in the above descriptions to facilitate the understanding of the present invention, the values are just examples and other appropriate values may also be used unless otherwise mentioned. Grouping of subject matter in the above descriptions is not essential for the present invention. For example, subject matter described in two or more sections may be combined as necessary, and subject matter described in one section may be applied to subject matter described in another section unless they contradict each other. Boundaries of functional units or processing units in functional block diagrams do not necessarily correspond to boundaries of physical components. Operations of multiple functional units may be performed by one physical component, and an operation of one functional unit may be performed by multiple physical components. The order of steps in sequence charts and flowcharts described in the embodiments may be changed unless they do not become inconsistent. Although functional block diagrams are used to describe the user device UE and the base station eNB, the user device UE and the base station eNB may be implemented by hardware, software, or a combination of them. Software to be executed by a processor of the user device UE and software to be executed by a processor of the base station eNB according to the embodiments of the present invention may be stored in any appropriate storage medium such as a random access memory (RAM), a flash memory, a read-only memory (ROM), an EPROM, an EEPROM, a register, a hard disk drive (HDD), a removable disk, a CD-ROM, a database, or a server.
- In the embodiments, PCMAX _ L is an example of a lower limit of maximum transmission power, and PCMAX _ H is an example of an upper limit of maximum transmission power.
- The present application is based on and claims the benefit of priority of Japanese Patent Application No. 2015-164257 filed on Aug. 21, 2015, the entire contents of which are hereby incorporated herein by reference.
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- eNB Base station
- UE User device
- 101 Signal transmitter
- 102 Signal receiver
- 103 Calculator
- 201 Signal transmitter
- 202 Signal receiver
- 203 Instructor
- 301 RF module
- 302 BB processing module
- 303 UE control module
- 401 RF module
- 402 BB processing module
- 403 Device control module
- 404 Communication IF
Claims (10)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP2015164257 | 2015-08-21 | ||
JP2015-164257 | 2015-08-21 | ||
PCT/JP2016/061319 WO2017033490A1 (en) | 2015-08-21 | 2016-04-06 | User device, base station, communication method, and instruction method |
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CN112351483A (en) * | 2020-10-30 | 2021-02-09 | 广东小天才科技有限公司 | Intelligent power saving method, system, equipment and storage medium for LTE terminal |
US10985966B2 (en) * | 2016-08-09 | 2021-04-20 | Panasonic Intellectual Property Corporation Of America | Terminal and communication method |
US11743840B2 (en) * | 2017-05-26 | 2023-08-29 | Qualcomm Incorporated | Power limit determination for carrier aggregation with shortened transmission time intervals |
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EP3536054B1 (en) * | 2016-11-04 | 2021-10-27 | Telefonaktiebolaget LM Ericsson (publ) | Deriving configured output power with different tti |
JP6963026B2 (en) * | 2017-03-24 | 2021-11-05 | エルジー エレクトロニクス インコーポレイティドLg Electronics Inc. | Power allocation method for terminals with multiple carriers and terminals that use the above method |
WO2018176396A1 (en) * | 2017-03-31 | 2018-10-04 | Nec Corporation | Methods, terminal device, and apparatuses for uplink power control and receiving |
JP6938625B2 (en) * | 2017-05-12 | 2021-09-22 | 株式会社Nttドコモ | Terminals, wireless communication methods, base stations and systems |
JP6911204B2 (en) | 2017-12-01 | 2021-07-28 | テレフオンアクチーボラゲット エルエム エリクソン(パブル) | Setting the maximum transmission power for dual connectivity |
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Also Published As
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JP7132972B2 (en) | 2022-09-07 |
JP2020110017A (en) | 2020-07-16 |
JPWO2017033490A1 (en) | 2018-06-07 |
US10893489B2 (en) | 2021-01-12 |
EP3340698A1 (en) | 2018-06-27 |
FI3340698T3 (en) | 2023-04-24 |
CN107852681B (en) | 2021-06-01 |
EP3340698A4 (en) | 2019-04-10 |
CN107852681A (en) | 2018-03-27 |
EP3340698B1 (en) | 2023-03-08 |
WO2017033490A1 (en) | 2017-03-02 |
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